Chapter Four - Expulsion of charged particles by radiofrequency fields

Chapter 4 Transporting Charged Particles in Radiofrequency Fields

Combination of cosmic electromagnetic fields (a cosmic source of energy), static magnetic fields (a ‘restoring force’ source in a flight vehicle converter), and cosmic charged particles (which have a general cosmic presence) can be used to accelerate charged particles to high energies in a limited space of a flight vehicle. The expulsion of such energetic particles by a chaotic gun effect can represent a reaction force which may be more reasonable than a ‘vacuum propeller reaction force’. In quantum terms, we can assert that the Comptonization of ubiquitous cosmic (real) photons can be realized by a second order Fermi (stochastic) acceleration mechanism which extracts energy from electromagnetic fields. The nonlinear interaction between the relativistic charged cosmic particles and the composite field (cosmic photons and vehicle static magnetic field) represent the starting point for the present paper. The accelerating process is described by a set of coupled nonlinear equations for electromagnetic fields and charged particles, which are similar with the equations for three coupled oscillators. The competition between these two (restoring and accelerating) forces can lead to a chaotic gun effect (i.e. a sudden expulsion of a particle from the system in a certain direction) which represents an energetic transfer of energy between charged particles and cosmic photons. Indeed, following numerical experiments, we demonstrate that there exists a continuous exchange of energy between cosmic photons and charged particles in the presence of a suitable chosen vehicle magnetic field. The advantages of the present method of obtaining a reaction force by a chaotic gun effect are represented by the possibilities of computer simulations and also of laboratory experiments.

Confinement of plasma by radio-frequency electro-magnetic fields

Isolating neutral and charged particles from the environment is essential in precision experiments. For decades, this has been achieved by trapping ions with radio-frequency (RF) fields and neutral particles with optical fields. Recently, the trapping of ions by interaction with light has been demonstrated. This might permit the advantages of optical trapping and ions to be combined. For example, we would benefit from superimposing optical traps to investigate ensembles of ions and atoms in the absence of any RF fields and from the versatile and scalable trapping geometries featured by optical lattices. In particular, ions provide individual addressability, and electronic and motional degrees of freedom that can be coherently controlled and detected via high-fidelity, state-dependent operations. Their long-range Coulomb interaction is significantly larger compared to those of neutral atoms and molecules. This enables ultra-cold interaction and the chemistry of trapped ions and atoms to be studied, as well as providing a novel platform for higher-dimensional experimental quantum simulations. The aim of this topical review is to present the current state of the art and to discuss the current challenges and prospects of the emerging field.

RF average power measurement system at the S-DALINAC

We have studied the compression and structure of compressed monolayers of sulfate polystyrene latex particles on air/water and octane/water interfaces. If compressed sufficiently (on a Langmuir trough) the monolayers at air/water surfaces give rafts of hexagonally packed particles, while those at oil/water interfaces undergo a transition from the originally hexagonal to a rhombohedral structure. We have found that beyond collapse the particle monolayers on both air/water and octane/water interfaces fold and corrugate, and there is no expulsion of individual particles or particle aggregates from the interface. In the case of air/water interfaces, the structuring of particle monolayers (below collapse) was found to be very sensitive to the electrolyte concentration in the aqueous phase. At low electrolyte concentration, a fairly ordered structure resulting from the interparticle repulsion was observed, while at high electrolyte concentration, the particles form 2D clusters. In marked contrast, particle mono...

This article provides an introduction to Fourier transform-based mass spectrometry. The key performance characteristics of Fourier transform-based mass spectrometry, mass accuracy and resolution, are presented in the view of how they impact the interpretation of measurements in proteomic applications. The theory and principles of operation of two types of mass analyzer, Fourier transform ion cyclotron resonance and Orbitrap, are described. Major benefits as well as limitations of Fourier transform-based mass spectrometry technology are discussed in the context of practical sample analysis, and illustrated with examples included as figures in this text and in the accompanying slide set. Comparisons highlighting the performance differences between the two mass analyzers are made where deemed useful in assisting the user with choosing the most appropriate technology for an application. Recent developments of these high-performing mass spectrometers are mentioned to provide a future outlook.

Summary form only given. Acceleration of charged particles exploiting the large optical field strength of short laser pulses and the proximity of a dielectric structure has been envisioned to revolutionize particle accelerators [1,2]. Direct acceleration by the optical carrier field of the laser can take place in the vicinity of a grating, also known as the inverse Smith-Purcell effect [3], which has been observed at a metal grating with a terahertz radiation source, however, the acceleration gradient was small (keV/m) [4]. Dielectrics allow much larger acceleration gradients and hence much smaller accelerators due to their orders of magnitude higher damage threshold in the optical regime as compared to metals. Using dielectric gratings as an optical accelerator has been proposed by Plettner et al. [5]. We observe direct laser acceleration of non-relativistic 28 keV electrons close to a single fused-silica transmission grating that is illuminated by Titanium:sapphire laser pulses from below (see Fig. 1a-c). Our findings represent the first demonstration of realistically scalable laser acceleration and of the inverse Smith-Purcell effect in the optical regime. The observed maximum acceleration gradient of 25 MeV/m (see Fig. 1d) is already comparable to state-of-the-art linear accelerators operating with radio-frequency fields. Our work represents the decisive step towards an all-optical linear accelerator that may allow building table-top free electron lasers [6] and other electron optical devices.

Particle accelerators served for many years as the main tool for nuclear physics research. The principle of particle accelerators is production of ions, accelerating and focusing them by electric or magnetic fields, and a nuclear reaction at a target. An accelerator for atomic particles consists of an ion source and a means for producing electric fields to accelerate the charged particles produced in the source. Emission can be obtained from heavy tungsten or tantalum filaments or from oxide-coated cathodes. This source of electrons makes it possible to operate the arc at considerably lower potentials than required for the canal-ray discharge. A radiofrequency discharge ion source utilizes the electrode less discharge produced in gases by radiofrequency fields. An axial magnetic field is used to enhance the ion yield. An electron oscillation ion source utilizes electron oscillations to increase the density in the discharge.

Afterglows in low pressure mercury arc vapour which remain visible for many seconds (T, which is defined as the time of persistence) can be produced by applying a radiofrequency field to the decaying discharge. T has been measured for different arc currents and also for different times of excitation of the arc. T increases if there is a longitudinal magnetic field, indicating that part of the decay, which may be substantial in some instances, is due directly or indirectly to diffusion of charged particles to the wall. The effect on T of varying the radiofrequency power and the strength of the magnetic field are described and discussed briefly, together with a retroactive effect of the decaying discharge on the voltage of the oscillator.

Nanodrugs selectively delivered to a tumor site can be activated by radiation for drug release, or nanoparticles (NPs) can be used as a drug themselves by producing biological damage in cancer cells through thermal, mechanical ablations or charged particle emission. Radio-frequency (RF) waves have an excellent ability to penetrate into the human body without causing healthy tissue damage, which provides a great opportunity to activate/heat NPs delivered inside the body as a contrast agent for diagnosis and treatment purposes. However the heating of NPs in the RF range of the spectrum is controversial in the research community because of the low power load of RF waves and low absorption of NPs in the RF range. To resolve these weaknesses in the RF activation of NPs and dramatically increase absorption of contrast agents in tumor, we suggest aggregating the nanoclusters inside or on the surface of the cancer cells. We simulate space distribution of temperature changes inside and outside metal and dielectric nanopraticles/nanoclusters, determine the number of nanoparticles needed to form a cluster, and estimate the thermal damage area produced in surrounding medium by nanopraticles/nanoclusters heated in the RF field.

The horizontal and vertical dispersion of passive particles in a decaying circular vortex in a rotating system is investigated analytically and numerically. The vortex decay is due to lateral viscosity and bottom friction effects (associated with the Ekman boundary layer). The vortex model comprises the three-dimensional velocity field, where the azimuthal component is much larger than the radial and vertical components, so the structure remains circular. The particles are dispersed by the deterministic velocity field plus stochastic perturbations. The analytical model allows the examination of frictional effects separately. The experiments show that an initial point charge of particles is dispersed around the vortex. The role of lateral viscosity is to delay the angular distribution of the particles. Bottom friction, on the other hand, generates radial motions, thus inducing outward advection in cyclones and inward advection in anticyclones. The intensity of lateral and bottom friction slows down the expulsion or retention of particles. Regarding vertical dispersion, cyclonic vortices can lift particles by a substantial fraction of the fluid column, while anticyclones sink particles as in a bathtub vortex. It is shown that the vertical distributions of the particles are significantly affected by the strength of the decaying mechanisms. Some consequences for the dispersion of tracers in oceanic vortices are discussed.

Particle Accelerators

8 - Particle Accelerators

Chapter 3 Transporting Charged Particle Beams in Static Fields